An Invitation to Enter a New Field of Physics
Richard
P. Feynman
This is a transcript of the classic
talk that Richard Feynman gave on December 29th 1959 at the annual meeting of
the American Physical Society at the California Institute of
Technology (Caltech). This was
first published in the February 1960 issue of Caltech's Engineering and Science, which owns the copyright.
Richard Feynman in 1959.
Introduction
I imagine experimental physicists must often look
with envy at men like Kamerlingh Onnes, who discovered a field like low
temperature superconductivity, which seems to be bottomless and in which one can go down and down.
Such a man is then a leader and has some temporary monopoly in a scientific
adventure. Percy Bridgman, in designing a way to obtain higher pressures,
opened up another new field and was able to move into it and to lead us all
along. The development of ever higher vacuum was a continuing development of
the same kind.
I would like to
describe a field, in which little has been done, but in which an enormous
amount can be done in principle. This field is not quite the same as the others
in that it will not tell us much of fundamental physics (in the sense of, “What
are the strange particles?”) but it is more like solid-state physics in the
sense that it might tell us much of great interest about the strange phenomena
that occur in complex situations. Furthermore, a point that is most important
is that it would have an enormous number of technical applications.
What I want to
talk about is the problem of manipulating and controlling things on a small
scale.
As soon as I
mention this, people tell me about miniaturization, and how far it has
progressed today. They tell me about electric motors that are the size of the
nail on your small finger. And there is a device on the market, they tell me,
by which you can write the Lord's Prayer on the head of a pin. But that's
nothing; that's the most primitive, halting step in the direction I intend to
discuss. It is a staggeringly small world that is below. In the year 2000, when
they look back at this age, they will wonder why it was not until the year 1960
that anybody began seriously to move in this direction.
Why cannot we
write the entire 24 volumes of the Encyclopedia Brittanica on the head of a
pin?
Let's see what
would be involved. The head of a pin is a sixteenth of an inch across. If you
magnify it by 25,000 diameters, the area of the head of the pin is then equal
to the area of all the pages of the Encyclopedia Brittanica. Therefore, all it
is necessary to do is to reduce in size all the writing in the Encyclopaedia by
25,000 times. Is that possible? The resolving power of the eye is about 1/120
of an inch---that is roughly the diameter of one of the little dots on the fine
half-tone reproductions in the Encyclopedia. This, when you demagnify it by
25,000 times, is still 80 angstroms in diameter---32 atoms across, in an
ordinary metal. In other words, one of those dots still would contain in its
area 1,000 atoms. So, each dot can easily be adjusted in size as required by
the photoengraving, and there is no question that there is enough room on the
head of a pin to put all of the Encyclopedia Brittanica.
Furthermore, it
can be read if it is so written. Let's imagine that it is written in raised
letters of metal; that is, where the black is in the Encyclopedia, we have
raised letters of metal that are actually 1/25,000 of their ordinary size. How
would we read it?
If we had
something written in such a way, we could read it using techniques in common
use today. (They will undoubtedly find a better way when we do actually have it
written, but to make my point conservatively I shall just take techniques we
know today.) We would press the metal into a plastic material and make a mold
of it, then peel the plastic off very carefully, evaporate silica into the
plastic to get a very thin film, then shadow it by evaporating gold at an angle
against the silica so that all the little letters will appear clearly, dissolve
the plastic away from the silica film, and then look through it with an
electron microscope!
There is no
question that if the thing were reduced by 25,000 times in the form of raised
letters on the pin, it would be easy for us to read it today. Furthermore;
there is no question that we would find it easy to make copies of the master;
we would just need to press the same metal plate again into plastic and we
would have another copy.
How do we write small?
The next question is: How do we write it? We have no
standard technique to do this now. But let me argue that it is not as difficult
as it first appears to be. We can reverse the lenses of the electron microscope
in order to demagnify as well as magnify. A source of ions, sent through the microscope
lenses in reverse, could be focused to a very small spot. We could write with
that spot like we write in a TV cathode ray oscilloscope, by going across in
lines, and having an adjustment which determines the amount of material which
is going to be deposited as we scan in lines.
This method
might be very slow because of space charge limitations. There will be more
rapid methods. We could first make, perhaps by some photo process, a screen
which has holes in it in the form of the letters. Then we would strike an arc
behind the holes and draw metallic ions through the holes; then we could again
use our system of lenses and make a small image in the form of ions, which
would deposit the metal on the pin.
A simpler way
might be this (though I am not sure it would work): We take light and, through
an optical microscope running backwards, we focus it onto a very small
photoelectric screen. Then electrons come away from the screen where the light
is shining. These electrons are focused down in size by the electron microscope
lenses to impinge directly upon the surface of the metal. Will such a beam etch
away the metal if it is run long enough? I don't know. If it doesn't work for a
metal surface, it must be possible to find some surface with which to coat the original
pin so that, where the electrons bombard, a change is made which we could
recognize later.
There is no
intensity problem in these devices---not what you are used to in magnification,
where you have to take a few electrons and spread them over a bigger and bigger
screen; it is just the opposite. The light which we get from a page is
concentrated onto a very small area so it is very intense. The few electrons
which come from the photoelectric screen are demagnified down to a very tiny
area so that, again, they are very intense. I don't know why this hasn't been
done yet!
That's the
Encyclopedia Brittanica on the head of a pin, but let's consider all the books
in the world. The Library of Congress has approximately 9 million volumes; the
British Museum Library has 5 million volumes; there are also 5 million volumes
in the National Library in France. Undoubtedly there are duplications, so let
us say that there are some 24 million volumes of interest in the world.
What would
happen if I print all this down at the scale we have been discussing? How much
space would it take? It would take, of course, the area of about a million
pinheads because, instead of there being just the 24 volumes of the
Encyclopaedia, there are 24 million volumes. The million pinheads can be put in
a square of a thousand pins on a side, or an area of about 3 square yards. That
is to say, the silica replica with the paper-thin backing of plastic, with
which we have made the copies, with all this information, is on an area of
approximately the size of 35 pages of the Encyclopaedia. That is about half as
many pages as there are in this magazine. All of the information which all of
mankind has every recorded in books can be carried around in a pamphlet in your
hand---and not written in code, but a simple reproduction of the original
pictures, engravings, and everything else on a small scale without loss of
resolution.
What would our
librarian at Caltech say, as she runs all over from one building to another, if
I tell her that, ten years from now, all of the information that she is
struggling to keep track of--- 120,000 volumes, stacked from the floor to the
ceiling, drawers full of cards, storage rooms full of the older books---can be
kept on just one library card! When the University of Brazil, for example,
finds that their library is burned, we can send them a copy of every book in
our library by striking off a copy from the master plate in a few hours and
mailing it in an envelope no bigger or heavier than any other ordinary air mail
letter.
Now, the name
of this talk is “There is Plenty of Room at the Bottom”---not just “There is Room at the Bottom.” What I
have demonstrated is that there is room---that you can decrease the size of things in a practical way. I
now want to show that there is plenty of room. I will not now discuss how we are going to do it, but only what
is possible in principle---in other words, what is possible according to the
laws of physics. I am not inventing anti-gravity, which is possible someday
only if the laws are not what we think. I am telling you what could be done if
the laws are what we think; we are not doing it simply because we haven't yet gotten
around to it.
Information on a small scale
Suppose that, instead of trying to reproduce the
pictures and all the information directly in its present form, we write only
the information content in a code of dots and dashes, or something like that,
to represent the various letters. Each letter represents six or seven ``bits''
of information; that is, you need only about six or seven dots or dashes for
each letter. Now, instead of writing everything, as I did before, on the surface of the head of
a pin, I am going to use the interior of the material as well.
Let us
represent a dot by a small spot of one metal, the next dash, by an adjacent
spot of another metal, and so on. Suppose, to be conservative, that a bit of
information is going to require a little cube of atoms 5 times 5 times 5---that
is 125 atoms. Perhaps we need a hundred and some odd atoms to make sure that
the information is not lost through diffusion, or through some other process.
I have
estimated how many letters there are in the Encyclopaedia, and I have assumed
that each of my 24 million books is as big as an Encyclopaedia volume, and have
calculated, then, how many bits of information there are (10^15). For each bit
I allow 100 atoms. And it turns out that all of the information that man has carefully
accumulated in all the books in the world can be written in this form in a cube
of material one two-hundredth of an inch wide--- which is the barest piece of
dust that can be made out by the human eye. So there is plenty of room at the bottom! Don't
tell me about microfilm!
This
fact---that enormous amounts of information can be carried in an exceedingly
small space---is, of course, well known to the biologists, and resolves the
mystery which existed before we understood all this clearly, of how it could be
that, in the tiniest cell, all of the information for the organization of a
complex creature such as ourselves can be stored. All this
information---whether we have brown eyes, or whether we think at all, or that
in the embryo the jawbone should first develop with a little hole in the side
so that later a nerve can grow through it---all this information is contained
in a very tiny fraction of the cell in the form of long-chain DNA molecules in
which approximately 50 atoms are used for one bit of information about the
cell.
Better electron microscopes
If I have written in a code, with 5 times 5 times 5
atoms to a bit, the question is: How could I read it today? The electron
microscope is not quite good enough, with the greatest care and effort, it can
only resolve about 10 angstroms. I would like to try and impress upon you while
I am talking about all of these things on a small scale, the importance of
improving the electron microscope by a hundred times. It is not impossible; it
is not against the laws of diffraction of the electron. The wave length of the
electron in such a microscope is only 1/20 of an angstrom. So it should be
possible to see the individual atoms. What good would it be to see individual
atoms distinctly?
We have friends
in other fields---in biology, for instance. We physicists often look at them
and say, “You know the reason you fellows are making so little progress?'”
(Actually I don't know any field where they are making more rapid progress than
they are in biology today.) ``You should use more mathematics, like we do.''
They could answer us---but they're polite, so I'll answer for them: “What you should do in order for us to make more rapid progress is
to make the electron microscope 100 times better.'”
What are the
most central and fundamental problems of biology today? They are questions
like: What is the sequence of bases in the DNA? What happens when you have a
mutation? How is the base order in the DNA connected to the order of amino
acids in the protein? What is the structure of the RNA; is it single-chain or
double-chain, and how is it related in its order of bases to the DNA? What is
the organization of the microsomes? How are proteins synthesized? Where does
the RNA go? How does it sit? Where do the proteins sit? Where do the amino
acids go in? In photosynthesis, where is the chlorophyll; how is it arranged;
where are the carotenoids involved in this thing? What is the system of the
conversion of light into chemical energy?
It is very easy
to answer many of these fundamental biological questions; you just look at the thing! You will see
the order of bases in the chain; you will see the structure of the microsome.
Unfortunately, the present microscope sees at a scale which is just a bit too
crude. Make the microscope one hundred times more powerful, and many problems
of biology would be made very much easier. I exaggerate, of course, but the
biologists would surely be very thankful to you---and they would prefer that to
the criticism that they should use more mathematics.
The theory of
chemical processes today is based on theoretical physics. In this sense,
physics supplies the foundation of chemistry. But chemistry also has analysis.
If you have a strange substance and you want to know what it is, you go through
a long and complicated process of chemical analysis. You can analyze almost
anything today, so I am a little late with my idea. But if the physicists
wanted to, they could also dig under the chemists in the problem of chemical
analysis. It would be very easy to make an analysis of any complicated chemical
substance; all one would have to do would be to look at it and see where the
atoms are. The only trouble is that the electron microscope is one hundred
times too poor. (Later, I would like to ask the question: Can the physicists do
something about the third problem of chemistry---namely, synthesis? Is there a physical way to
synthesize any chemical substance?
The reason the
electron microscope is so poor is that the f- value of the lenses is only 1
part to 1,000; you don't have a big enough numerical aperture. And I know that
there are theorems which prove that it is impossible, with axially symmetrical
stationary field lenses, to produce an f-value any bigger than so and so; and
therefore the resolving power at the present time is at its theoretical
maximum. But in every theorem there are assumptions. Why must the field be
symmetrical? I put this out as a challenge: Is there no way to make the
electron microscope more powerful?
The marvellous biological system
The biological example of writing information on a
small scale has inspired me to think of something that should be possible.
Biology is not simply writing information; it is doing something about it. A biological system can be exceedingly
small. Many of the cells are very tiny, but they are very active; they
manufacture various substances; they walk around; they wiggle; and they do all
kinds of marvellous things---all on a very small scale. Also, they store
information. Consider the possibility that we too can make a thing very small
which does what we want---that we can manufacture an object that manoeuvres at
that level!
There may even
be an economic point to this business of making things very small. Let me
remind you of some of the problems of computing machines. In computers we have
to store an enormous amount of information. The kind of writing that I was
mentioning before, in which I had everything down as a distribution of metal,
is permanent. Much more interesting to a computer is a way of writing, erasing,
and writing something else. (This is usually because we don't want to waste the
material on which we have just written. Yet if we could write it in a very
small space, it wouldn't make any difference; it could just be thrown away
after it was read. It doesn't cost very much for the material).
Miniaturizing the computer
I don't know how to do this on a small scale in a
practical way, but I do know that computing machines are very large; they fill
rooms. Why can't we make them very small, make them of little wires, little
elements---and by little, I mean little.
For instance, the wires should be 10 or 100 atoms in diameter, and the circuits
should be a few thousand angstroms across. Everybody who has analyzed the
logical theory of computers has come to the conclusion that the possibilities
of computers are very interesting---if they could be made to be more
complicated by several orders of magnitude. If they had millions of times as
many elements, they could make judgments. They would have time to calculate
what is the best way to make the calculation that they are about to make. They
could select the method of analysis which, from their experience, is better
than the one that we would give to them. And in many other ways, they would
have new qualitative features.
If I look at
your face I immediately recognize that I have seen it before. (Actually, my
friends will say I have chosen an unfortunate example here for the subject of
this illustration. At least I recognize that it is a man and not an apple.) Yet there is no machine which, with that speed, can take a picture of
a face and say even that it is a man; and much less that it is the same man
that you showed it before---unless it is exactly the same picture. If the face
is changed; if I am closer to the face; if I am further from the face; if the
light changes---I recognize it anyway. Now, this little computer I carry in my
head is easily able to do that. The computers that we build are not able to do
that. The number of elements in this bone box of mine are enormously greater
than the number of elements in our “wonderful'” computers. But our mechanical
computers are too big; the elements in this box are microscopic. I want to make
some that are submicroscopic.
If we wanted to
make a computer that had all these marvellous extra qualitative abilities, we
would have to make it, perhaps, the size of the Pentagon. This has several
disadvantages. First, it requires too much material; there may not be enough
germanium in the world for all the transistors which would have to be put into
this enormous thing. There is also the problem of heat generation and power
consumption; TVA would be needed to run the computer. But an even more
practical difficulty is that the computer would be limited to a certain speed.
Because of its large size, there is finite time required to get the information
from one place to another. The information cannot go any faster than the speed
of light---so, ultimately, when our computers get faster and faster and more
and more elaborate, we will have to make them smaller and smaller.
But there is
plenty of room to make them smaller. There is nothing that I can see in the
physical laws that says the computer elements cannot be made enormously smaller
than they are now. In fact, there may be certain advantages.
Miniaturization by evaporation
How can we make such a device? What kind of
manufacturing processes would we use? One possibility we might consider, since
we have talked about writing by putting atoms down in a certain arrangement,
would be to evaporate the material, then evaporate the insulator next to it.
Then, for the next layer, evaporate another position of a wire, another
insulator, and so on. So, you simply evaporate until you have a block of stuff
which has the elements--- coils and condensers, transistors and so on---of
exceedingly fine dimensions.
But I would
like to discuss, just for amusement, that there are other possibilities. Why
can't we manufacture these small computers somewhat like we manufacture the big
ones? Why can't we drill holes, cut things, solder things, stamp things out,
mold different shapes all at an infinitesimal level? What are the limitations
as to how small a thing has to be before you can no longer mold it? How many
times when you are working on something frustratingly tiny like your wife's
wrist watch, have you said to yourself, ``If I could only train an ant to do
this!'' What I would like to suggest is the possibility of training an ant to
train a mite to do this. What are the possibilities of small but movable
machines? They may or may not be useful, but they surely would be fun to make.
Consider any
machine---for example, an automobile---and ask about the problems of making an
infinitesimal machine like it. Suppose, in the particular design of the
automobile, we need a certain precision of the parts; we need an accuracy, let's
suppose, of 4/10,000 of an inch. If things are more inaccurate than that in the
shape of the cylinder and so on, it isn't going to work very well. If I make
the thing too small, I have to worry about the size of the atoms; I can't make
a circle of ``balls'' so to speak, if the circle is too small. So, if I make
the error, corresponding to 4/10,000 of an inch, correspond to an error of 10
atoms, it turns out that I can reduce the dimensions of an automobile 4,000
times, approximately---so that it is 1 mm. across. Obviously, if you redesign
the car so that it would work with a much larger tolerance, which is not at all
impossible, then you could make a much smaller device.
It is
interesting to consider what the problems are in such small machines. Firstly,
with parts stressed to the same degree, the forces go as the area you are
reducing, so that things like weight and inertia are of relatively no
importance. The strength of material, in other words, is very much greater in
proportion. The stresses and expansion of the flywheel from centrifugal force,
for example, would be the same proportion only if the rotational speed is
increased in the same proportion as we decrease the size. On the other hand,
the metals that we use have a grain structure, and this would be very annoying
at small scale because the material is not homogeneous. Plastics and glass and
things of this amorphous nature are very much more homogeneous, and so we would
have to make our machines out of such materials.
There are
problems associated with the electrical part of the system---with the copper
wires and the magnetic parts. The magnetic properties on a very small scale are
not the same as on a large scale; there is the ``domain'' problem involved. A
big magnet made of millions of domains can only be made on a small scale with
one domain. The electrical equipment won't simply be scaled down; it has to be
redesigned. But I can see no reason why it can't be redesigned to work again.
Problems of lubrication
Lubrication involves some interesting points. The effective viscosity of oil would be higher and higher in proportion as we went down (and if we increase the speed as much as we can). If we don't increase the speed so much, and change from oil to kerosene or some other fluid, the problem is not so bad. But actually we may not have to lubricate at all! We have a lot of extra force. Let the bearings run dry; they won't run hot because the heat escapes away from such a small device very, very rapidly.
This rapid heat
loss would prevent the gasoline from exploding, so an internal combustion
engine is impossible. Other chemical reactions, liberating energy when cold,
can be used. Probably an external supply of electrical power would be most
convenient for such small machines.
What would be
the utility of such machines? Who knows? Of course, a small automobile would
only be useful for the mites to drive around in, and I suppose our Christian
interests don't go that far. However, we did note the possibility of the
manufacture of small elements for computers in completely automatic factories,
containing lathes and other machine tools at the very small level. The small
lathe would not have to be exactly like our big lathe. I leave to your
imagination the improvement of the design to take full advantage of the
properties of things on a small scale, and in such a way that the fully
automatic aspect would be easiest to manage.
A friend of
mine (Albert R. Hibbs) suggests a very interesting possibility for relatively
small machines. He says that, although it is a very wild idea, it would be
interesting in surgery if you could swallow the surgeon. You put the mechanical
surgeon inside the blood vessel and it goes into the heart and ``looks''
around. (Of course the information has to be fed out.) It finds out which valve
is the faulty one and takes a little knife and slices it out. Other small
machines might be permanently incorporated in the body to assist some
inadequately-functioning organ.
Now comes the
interesting question: How do we make such a tiny mechanism? I leave that to
you. However, let me suggest one weird possibility. You know, in the atomic
energy plants they have materials and machines that they can't handle directly
because they have become radioactive. To unscrew nuts and put on bolts and so
on, they have a set of master and slave hands, so that by operating a set of
levers here, you control the ``hands'' there, and can turn them this way and
that so you can handle things quite nicely.
Most of these
devices are actually made rather simply, in that there is a particular cable,
like a marionette string, that goes directly from the controls to the
``hands.'' But, of course, things also have been made using servo motors, so
that the connection between the one thing and the other is electrical rather
than mechanical. When you turn the levers, they turn a servo motor, and it
changes the electrical currents in the wires, which repositions a motor at the
other end.
Now, I want to
build much the same device---a master-slave system which operates electrically.
But I want the slaves to be made especially carefully by modern large-scale
machinists so that they are one-fourth the scale of the ``hands'' that you
ordinarily manoeuvre. So you have a scheme by which you can do things at one- quarter
scale anyway---the little servo motors with little hands play with little nuts
and bolts; they drill little holes; they are four times smaller. Aha! So I
manufacture a quarter-size lathe; I manufacture quarter-size tools; and I make,
at the one-quarter scale, still another set of hands again relatively
one-quarter size! This is one-sixteenth size, from my point of view. And after
I finish doing this I wire directly from my large-scale system, through
transformers perhaps, to the one-sixteenth-size servo motors. Thus I can now
manipulate the one-sixteenth size hands.
Well, you get
the principle from there on. It is rather a difficult program, but it is a
possibility. You might say that one can go much farther in one step than from
one to four. Of course, this has all to be designed very carefully and it is
not necessary simply to make it like hands. If you thought of it very
carefully, you could probably arrive at a much better system for doing such
things.
If you work
through a pantograph, even today, you can get much more than a factor of four
in even one step. But you can't work directly through a pantograph which makes
a smaller pantograph which then makes a smaller pantograph---because of the
looseness of the holes and the irregularities of construction. The end of the
pantograph wiggles with a relatively greater irregularity than the irregularity
with which you move your hands. In going down this scale, I would find the end
of the pantograph on the end of the pantograph on the end of the pantograph shaking
so badly that it wasn't doing anything sensible at all.
At each stage,
it is necessary to improve the precision of the apparatus. If, for instance,
having made a small lathe with a pantograph, we find its lead screw
irregular---more irregular than the large-scale one---we could lap the lead
screw against breakable nuts that you can reverse in the usual way back and
forth until this lead screw is, at its scale, as accurate as our original lead
screws, at our scale.
We can make
flats by rubbing unflat surfaces in triplicates together---in three pairs---and
the flats then become flatter than the thing you started with. Thus, it is not
impossible to improve precision on a small scale by the correct operations. So,
when we build this stuff, it is necessary at each step to improve the accuracy
of the equipment by working for awhile down there, making accurate lead screws,
Johansen blocks, and all the other materials which we use in accurate machine
work at the higher level. We have to stop at each level and manufacture all the
stuff to go to the next level---a very long and very difficult program. Perhaps
you can figure a better way than that to get down to small scale more rapidly.
Yet, after all
this, you have just got one little baby lathe four thousand times smaller than
usual. But we were thinking of making an enormous computer, which we were going
to build by drilling holes on this lathe to make little washers for the
computer. How many washers can you manufacture on this one lathe?
A hundred tiny hands
When I make my first set of slave ``hands'' at
one-fourth scale, I am going to make ten sets. I make ten sets of ``hands,''
and I wire them to my original levers so they each do exactly the same thing at
the same time in parallel. Now, when I am making my new devices one-quarter
again as small, I let each one manufacture ten copies, so that I would have a
hundred ``hands'' at the 1/16th size.
Where am I
going to put the million lathes that I am going to have? Why, there is nothing
to it; the volume is much less than that of even one full-scale lathe. For
instance, if I made a billion little lathes, each 1/4000 of the scale of a
regular lathe, there are plenty of materials and space available because in the
billion little ones there is less than 2 percent of the materials in one big
lathe.
It doesn't cost
anything for materials, you see. So I want to build a billion tiny factories,
models of each other, which are manufacturing simultaneously, drilling holes,
stamping parts, and so on.
As we go down
in size, there are a number of interesting problems that arise. All things do
not simply scale down in proportion. There is the problem that materials stick
together by the molecular (Van der Waals) attractions. It would be like this:
After you have made a part and you unscrew the nut from a bolt, it isn't going
to fall down because the gravity isn't appreciable; it would even be hard to
get it off the bolt. It would be like those old movies of a man with his hands
full of molasses, trying to get rid of a glass of water. There will be several
problems of this nature that we will have to be ready to design for.
Rearranging the atoms
But I am not afraid to consider the final question
as to whether, ultimately---in the great future---we can arrange the atoms the
way we want; the very atoms,
all the way down! What would happen if we could arrange the atoms one by one
the way we want them (within reason, of course; you can't put them so that they
are chemically unstable, for example).
Up to now, we
have been content to dig in the ground to find minerals. We heat them and we do
things on a large scale with them, and we hope to get a pure substance with
just so much impurity, and so on. But we must always accept some atomic
arrangement that nature gives us. We haven't got anything, say, with a “checkerboard'”
arrangement, with the impurity atoms exactly arranged 1,000 angstroms apart, or
in some other particular pattern.
What could we
do with layered structures with just the right layers? What would the
properties of materials be if we could really arrange the atoms the way we want
them? They would be very interesting to investigate theoretically. I can't see
exactly what would happen, but I can hardly doubt that when we have some control of the arrangement of things on
a small scale we will get an enormously greater range of possible properties
that substances can have, and of different things that we can do.
Consider, for
example, a piece of material in which we make little coils and condensers (or
their solid state analogs) 1,000 or 10,000 angstroms in a circuit, one right
next to the other, over a large area, with little antennas sticking out at the
other end---a whole series of circuits. Is it possible, for example, to emit
light from a whole set of antennas, like we emit radio waves from an organized
set of antennas to beam the radio programs to Europe? The same thing would be
to beam the light out
in a definite direction with very high intensity. (Perhaps such a beam is not
very useful technically or economically.)
I have thought
about some of the problems of building electric circuits on a small scale, and
the problem of resistance is serious. If you build a corresponding circuit on a
small scale, its natural frequency goes up, since the wave length goes down as
the scale; but the skin depth only decreases with the square root of the scale
ratio, and so resistive problems are of increasing difficulty. Possibly we can
beat resistance through the use of superconductivity if the frequency is not
too high, or by other tricks.
Atoms in a small world
When we get to the very, very small world---say
circuits of seven atoms---we have a lot of new things that would happen that
represent completely new opportunities for design. Atoms on a small scale
behave like nothingon
a large scale, for they satisfy the laws of quantum mechanics. So, as we go
down and fiddle around with the atoms down there, we are working with different
laws, and we can expect to do different things. We can manufacture in different
ways. We can use, not just circuits, but some system involving the quantized
energy levels, or the interactions of quantized spins, etc.
Another thing
we will notice is that, if we go down far enough, all of our devices can be
mass produced so that they are absolutely perfect copies of one another. We
cannot build two large machines so that the dimensions are exactly the same.
But if your machine is only 100 atoms high, you only have to get it correct to
one-half of one percent to make sure the other machine is exactly the same
size---namely, 100 atoms high!
At the atomic
level, we have new kinds of forces and new kinds of possibilities, new kinds of
effects. The problems of manufacture and reproduction of materials will be
quite different. I am, as I said, inspired by the biological phenomena in which
chemical forces are used in repetitious fashion to produce all kinds of weird
effects (one of which is the author).
The principles
of physics, as far as I can see, do not speak against the possibility of manoeuvring
things atom by atom. It is not an attempt to violate any laws; it is something,
in principle, that can be done; but in practice, it has not been done because
we are too big.
Ultimately, we
can do chemical synthesis. A chemist comes to us and says, ``Look, I want a
molecule that has the atoms arranged thus and so; make me that molecule.'' The
chemist does a mysterious thing when he wants to make a molecule. He sees that
it has got that ring, so he mixes this and that, and he shakes it, and he
fiddles around. And, at the end of a difficult process, he usually does succeed
in synthesizing what he wants. By the time I get my devices working, so that we
can do it by physics, he will have figured out how to synthesize absolutely
anything, so that this will really be useless.
But it is
interesting that it would be, in principle, possible (I think) for a physicist
to synthesize any chemical substance that the chemist writes down. Give the
orders and the physicist synthesizes it. How? Put the atoms down where the
chemist says, and so you make the substance. The problems of chemistry and
biology can be greatly helped if our ability to see what we are doing, and to
do things on an atomic level, is ultimately developed---a development which I
think cannot be avoided.
Now, you might
say, “Who should do this and why should they do it?” Well, I pointed out a few
of the economic applications, but I know that the reason that you would do it
might be just for fun. But have some fun! Let's have a competition between
laboratories. Let one laboratory make a tiny motor which it sends to another
lab which sends it back with a thing that fits inside the shaft of the first
motor.
High school competition*
Just for the fun of it, and in order to get kids
interested in this field, I would propose that someone who has some contact
with the high schools think of making some kind of high school competition.
After all, we haven't even started in this field, and even the kids can write
smaller than has ever been written before. They could have competition in high
schools. The Los Angeles high school could send a pin to the Venice high school
on which it says, ``How's this?'' They get the pin back, and in the dot of the
``i'' it says, ``Not so hot.''
Perhaps this
doesn't excite you to do it, and only economics will do so. Then I want to do
something; but I can't do it at the present moment, because I haven't prepared
the ground. It is my intention to offer a prize of $1,000 to the first guy who
can take the information on the page of a book and put it on an area 1/25,000
smaller in linear scale in such manner that it can be read by an electron
microscope.
And I want to
offer another prize---if I can figure out how to phrase it so that I don't get
into a mess of arguments about definitions---of another $1,000 to the first guy
who makes an operating electric motor---a rotating electric motor which can be
controlled from the outside and, not counting the lead-in wires, is only 1/64
inch cube.
I do not expect
that such prizes will have to wait very long for claimants.
Richard Feynman's "Tiny Machines" Talk:
Here is an updated version of Richard Feynman's classic talk from 1984.
*
Feynman's offer did not go unnoticed and interestingly, in less than 6 months after Feynman laid the bait, an electrical engineer called Mr. William H. McLellan had actually invented a motor 1/64 of an inch long!
Rather embarrassed, Feynman signed over a $1,000 check and stating that he did not expect somebody to accomplish this so soon and was disapointed that no knew manufacturing techniques had to be developed to create such a tiny machine part.
Feynman then stated, rather shrewdly, to people that he would now not make good on his other offer of $1,000 to the first person who would write the first page of a book 1/25,000 times smaller in scale.
The reason? Feynman had gotten married and bought a house during those 6 months!
Feynman had little to worry about, for it took until 1985 when a graduate student called Tom Newman claimed the prize when he wrote the first page of Charles Dickens' A Tale of Two Cities at the required scale, on the head of a pin with a beam of electrons:
The difficult part of this is of course reading nanoscale print on the head of a pin. How did he do it? Why with an electron microscope of course, just as Feynman himself predicted way back in 1959!